From a64053509c062274577813cbe9b5977d6e2aaf33 Mon Sep 17 00:00:00 2001
From: Jeffrey Chien <chienjef@amazon.com>
Date: Wed, 6 Sep 2023 17:20:57 -0400
Subject: [PATCH] Add shared config fallback stat to agent info. (#842)

---
 cfg/aws/credentials.go          |  3 +++
 handlers/agentinfo/info.go      | 29 ++++++++++++++++++++++-------
 handlers/agentinfo/info_test.go | 13 +++++++++++++
 3 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/cfg/aws/credentials.go b/cfg/aws/credentials.go
index a2e3dc146a..34ab40f54a 100644
--- a/cfg/aws/credentials.go
+++ b/cfg/aws/credentials.go
@@ -18,6 +18,8 @@ import (
 	"github.com/aws/aws-sdk-go/aws/endpoints"
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/sts"
+
+	"github.com/aws/amazon-cloudwatch-agent/handlers/agentinfo"
 )
 
 const (
@@ -114,6 +116,7 @@ func getSession(config *aws.Config) *session.Session {
 		if len(found) > 0 {
 			log.Printf("W! Unused shared config file(s) found: %v. If you would like to use them, "+
 				"please update your common-config.toml.", found)
+			agentinfo.RecordSharedConfigFallback()
 		}
 	}
 	return ses
diff --git a/handlers/agentinfo/info.go b/handlers/agentinfo/info.go
index 581cc85f41..77d238d620 100644
--- a/handlers/agentinfo/info.go
+++ b/handlers/agentinfo/info.go
@@ -16,6 +16,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/aws/aws-sdk-go/aws"
@@ -47,6 +48,7 @@ var (
 	version                 = readVersionFile()
 	fullVersion             = getFullVersion(version)
 	id                      = uuid.NewString()
+	sharedConfigFallback    atomic.Bool
 )
 
 var isRunningAsRoot = defaultIsRunningAsRoot
@@ -65,13 +67,14 @@ type agentInfo struct {
 }
 
 type agentStats struct {
-	CpuPercent          *float64 `json:"cpu,omitempty"`
-	MemoryBytes         *uint64  `json:"mem,omitempty"`
-	FileDescriptorCount *int32   `json:"fd,omitempty"`
-	ThreadCount         *int32   `json:"th,omitempty"`
-	LatencyMillis       *int64   `json:"lat,omitempty"`
-	PayloadBytes        *int     `json:"load,omitempty"`
-	StatusCode          *int     `json:"code,omitempty"`
+	CpuPercent           *float64 `json:"cpu,omitempty"`
+	MemoryBytes          *uint64  `json:"mem,omitempty"`
+	FileDescriptorCount  *int32   `json:"fd,omitempty"`
+	ThreadCount          *int32   `json:"th,omitempty"`
+	LatencyMillis        *int64   `json:"lat,omitempty"`
+	PayloadBytes         *int     `json:"load,omitempty"`
+	StatusCode           *int     `json:"code,omitempty"`
+	SharedConfigFallback *int     `json:"scfb,omitempty"`
 }
 
 func New(groupName string) AgentInfo {
@@ -119,6 +122,7 @@ func (ai *agentInfo) RecordOpData(latency time.Duration, payloadBytes int, err e
 		stats.MemoryBytes = ai.memoryBytes()
 		stats.FileDescriptorCount = ai.fileDescriptorCount()
 		stats.ThreadCount = ai.threadCount()
+		stats.SharedConfigFallback = getSharedConfigFallback()
 		ai.nextUpdate = now.Add(updateInterval)
 	}
 
@@ -297,3 +301,14 @@ func isUsageDataEnabled() bool {
 func defaultIsRunningAsRoot() bool {
 	return os.Getuid() == 0
 }
+
+func RecordSharedConfigFallback() {
+	sharedConfigFallback.Store(true)
+}
+
+func getSharedConfigFallback() *int {
+	if sharedConfigFallback.Load() {
+		return aws.Int(1)
+	}
+	return nil
+}
diff --git a/handlers/agentinfo/info_test.go b/handlers/agentinfo/info_test.go
index 3a3e0eea6c..10e49ba602 100644
--- a/handlers/agentinfo/info_test.go
+++ b/handlers/agentinfo/info_test.go
@@ -147,6 +147,9 @@ func TestGetAgentStats(t *testing.T) {
 
 	stats.StatusCode = nil
 	assert.Empty(t, getAgentStats(stats))
+
+	stats.SharedConfigFallback = aws.Int(1)
+	assert.Equal(t, "\"scfb\":1", getAgentStats(stats))
 }
 
 func TestGetStatusCode(t *testing.T) {
@@ -233,3 +236,13 @@ func TestIsUsageDataEnabled(t *testing.T) {
 	t.Setenv(envconfig.CWAGENT_USAGE_DATA, "FALSE")
 	assert.False(t, getUsageDataEnabled())
 }
+
+func TestSharedConfigFallback(t *testing.T) {
+	defer sharedConfigFallback.Store(false)
+	assert.Nil(t, getSharedConfigFallback())
+	RecordSharedConfigFallback()
+	assert.Equal(t, 1, *(getSharedConfigFallback()))
+	RecordSharedConfigFallback()
+	RecordSharedConfigFallback()
+	assert.Equal(t, 1, *(getSharedConfigFallback()))
+}